Incinerator



April 25, 1950 s, LETVIN y A 2,504,991

INCINERATOR Y Filed Nov. 19. 1945 uvmvrog. Jamuc/ Lefwn ATTORNEY Patented Apr. 25, 1950 UNITED rum OFFICE;

(Granted under the act of March 3, 1883, as amendedA'p'ril 30, 1928; 37-0- 0. G. 757) t'o'r or furnace having a minimum amounto'f refractcry'lining.

Further objects and advantages o'fthis invention, as well as its construction, arrangement and operation; will be apparent from thefollowing description and claims in connection with the accompanying drawings, in which,

Figure 1 is a side elevation of the "furnac of tl'iis invention,

Figure 2 is a sectional view taken on the lines 2--2 ofFigure 1, and

Figure-3 is a partial front elevation of the furnace shown in Figure 1.

Figure- I shows anincinerator r furnace, generally designated as H), supported upon a base l-I,and having an ashpit door l2, a feed door It, and anexhaust outlet or stack It.

The-furnace 'fflys'hown in section in Figure 2, comprises "a distorted'funnel shaped inner metal shell I5, the small end It of which communicates with the stack 14. Around the inner shell I5 and spaced therefrom seas to form an annular air chamber, is an outer "metal shell or casing H, which may be laggedor coated with suitable insulating material Ila, such as amosite.

A grate l8 is located within the inner shell I 5, spaced a suflicient distance above the base H so a's't'o provide a suitable ashpit, and secured to "the inner shell 'as'at I'll. A fireboxfa'bove the grate comprises refractory side Walls. 2E3, which line the "inner shell I 5 for a distance above thergrate [8, the refractory material extending high enough to accommodate the quantity of material being burned when the furnace is oneranng 'u'nder normm conditions.- Above the grate T3 are two rows of apertures 22, whicheiitend "through the inner shell "t5 and the refractory side walls 211, and communicate between the firebox and the annular air chamber. These apertures 22 are preferably directed toward the center of the furnace and are slanted slightly upward in the direction of the ascending hot gases. Optionally the apertures 22' may be in.- stalled tangentially so as to impart a swirling or rotary motion to the. ascending gases. Another row of apertures 23' is provided in the inner shell [5, above the refractory side wall 29', to comm unicate between the annular air chamber and the combustion chamber. Air inlets are also providedjust above the base II as at 24' entering the ashpit below the grate I8.

The ashpit door I2 and feed door l3 are comprised of inner plates 25 and. an outer plate. 26 spaced therefrom, as shown. in Figure 1. If induced draft is. to be used, the inner plates 25 may contain a plurality of holes as at 2'! (Figure 3) for providing, additional air for combustion.

In operation, the furnace is 'fed through the door l3. Air for combustion is supplied by either fcrced'or induced draft. If induced draft is used an exhaust blower not shown) is installed in the stack"! 4:, and the annular space between theinner shell [5 and outer casing H is left open to the atmosphere at the top of the furnace. Air for combustion is: drawn down between the outer casing. I1 and inner shell 15, coolin the metal parts comprising the firebox andthecombustion chamber, and entering the furnace above the grate l3 through the apertures 22. Additional air for combustion is drawn through the inlets 2'4 and through the grate It. If holes'are provided through the feed door 53 and ashpit door !2 some air also enters at these points.

If forced draft is to be used a blower may be installed, and air ducts may be provided so as to supply air' irom the blower to the annular Space between the inner shell 55 and outer casing ['1' at the top of the furnace, with ducts prcvided'if desired communicating with the air inlets '24 below the grate 18. A portion of the air is then forced between the metal shells of the furnace providing cooling of the walls, and the remainder is forced through the grate it.

By using a furnace having inner and outer metal walls and supplying cooling air between them it is necessary to provide only a small amount of refractory lining within the furnace, thus cutting down materially on the total weight of the unit. Furthermore, due to the supply of preheated air introduced into the combustion space through the apertures above the grate, fast combustion is .maintained and a smaller unit can be employed to burn the same amount of material.

A furnace, constructed and operated according to the principles disclosed herein, and having an internal diameter of approximately four feet,

operated efiiciently and had the following operating characteristics:

Firing rate (lbs. per hr.) 500 Air flow through furnace (C. F. M.) 3800 Average outlet gas temp, F. 950 Maximum inner shell temp 840 Average inner shell temp, "F 668 Average outer casing temp, F. 145

Three rows of apertures were used in the inner shell above the grate and air was drawn in by induced draft. The unit weighed approximately 4000 pounds and occupied approximately 150 cubic feet.

Changes can be made in this inventlon'without departing from the spirit and scope thereof as set forth in the appended claims.

The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

What is claimed is:

1. An incinerator comprising an inner metal shell having an exhaust duct at its top, an insulated outer casing around the inner shell and spaced therefrom, the outer casing extending upwardly to a position near the exhaust duct, the space between the inner shell and outer casing being open to the atmosphere at the top, a feeding door in the inner shell and through the outer casing, a grate within the inner shell, a refractory lining within the shell adjacent the grate and extending upwardly a short distance there from, the inner shell having a plurality of apertures at spaced intervals for receiving air from the space between the inner shell and outer casing, the inner shell having some of the apertures in the area of the refractory lining and extending therethrough, the incinerator having an air passage at its base for receiving air below the grate.

2. An incinerator comprising an inner metal upright shell that tapers smaller in the upward direction and extends to include an exhaust duct,

an insulated outer casing around the inner shell and spaced therefrom, the outer casing extending upwardly to a position near the exhaust duct, the space between the inner shell and outer casing being open to the atmosphere at the top, a feeding door in the inner shell and through the outer casing, a grate within the inner shell, a refractory wall extending a short distance upwardly above the grate and lining a portion of the inner shell, the inner shell and the refractory wall having a plurality of apertures at spaced intervals through them, the inner shell having a plurality of apertures through it in the area above the refractory wall, the apertures being adapted to receive air from the space between the inner shell and outer casing, the incinerator having an air passage at its base for receiving air below the grate.

3. An incinerator comprising an upright inner metal shell that tapers smaller in the upward direction and extends to include an exhaust duct, an insulated outer casing around the inner shell and spaced therefrom, the outer casing extending upwardly to a position near the exhaust duct, the space between the inner shell and outer casing being open to the atmosphere at the top,

a feeding door in the inner shell and through the outer casing, a grate within the inner shell, a refractory wall extending a short distance above the grate and lining a portion of the inner shell, the inner shell having a plurality of apertures at spaced intervals in the area of the refractory wall and extending through the inner shell and refractory wall, the inner shell having a plurality of apertures extending through it at spaced intervals in the area above the refractory wall, the apertures being adapted to receive air from the space between the inner shell and outer casing, the incinerator having an air passage at its base for receiving air below the grate.

4. An incinerator composed of inner and outer metallic shells in spaced relation, the space between the inner and outer shell being open to the atmosphere at its end, a grate located in the inner shell, refractory material lining the interior surface of the inner shell for a portion of its vertical extent above the grate, the inner shell and refractory lining having apertures for the flow of air from the space between the shells,

the inner shell also having apertures above the refractory lining.

5. An incinerator comprising an upright inner metal shell, an outer metal casing around the shell spaced away therefrom and enclosing an air chamber around the shell in contact with the outer surface thereof, the shell being tapered in the upward direction to include an exhaust duct, the air chamber extending upwardly to a position near the exhaust duct and being open to the atmosphere at the top, the inner shell having a plurality of vertically spaced apertures extending from the air chamber into the inner shell.

6. In an incinerator as defined in claim 5, insulating material covering the exterior surface of the casing.

7. An incinerator comprising an inner metal shell, an outer casing, the shell and the casing being spaced to provide a passage therebetween which is open to the atmosphere at the top, whereby air delivered against the shell can move downward along the inner shell, and the shell having openings therethrough from the passage to the interior of the shell and below the region where the air is delivered against the shell whereby the air, which has cooled the shell and become warmed, can pass directly into the interior of the shell to assist combustion.

SAMUEL LETVIN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 516,017 La Rue Mar. 6, 1894 804,140 Lahan Nov. 7, 1905 1,131,188 Weaver Mar. 9, 1915 1,433,438 Watson Oct. 24, 1922 1,610,558 Lambert Dec. 14, 1926 1,622,431 Feigenbaum Mar. 29, 1927 2,010,460 McKinley Aug. 6, 1935 2,146,531 Craigie Feb. 7, 1939 2,161,412 Gregg June 6, 1939 2,393,855 Cheasley Jan. 29, 1946 

